The present invention relates to a bolt guiding device for a floating caliper disc brake, having at least one guide bolt that is supported in a brake carrier and mounted on a brake caliper, wherein the brake caliper is movably guided over the guide bolt in the axial direction thereof, wherein the bolt guiding device is disposed between an inner circumferential surface of a location hole of the brake carrier and an outer circumferential surface of the guide bolt accommodated therein, wherein the bolt guiding device comprises a slide bush, wherein one surface of the inner circumferential surface and external circumferential surface acts as a retaining surface on which the slide bush is retained, and wherein the other surface of the inner circumferential surface and external circumferential surface acts as a sliding surface on which the slide bush slides.
Such a bolt guiding device is prior art. In this respect reference is made to the document DE 103 41 095 A1, in which a bearing sleeve that receives a slide bush is inserted into the brake caliper. The slide bush is, as it were, permanently fixed in the brake caliper. The slide bush comprises a plurality of radial grooves running in circumferential direction and surrounded in each case by guiding surfaces lying closely adjacent to a guide bolt. It has however emerged that with this arrangement, particularly if the vehicle is stationary for a prolonged period, upon actuation of the brake a relatively high static friction has to be overcome first before the brake caliper can be moved. As a consequence of this, in such a situation relatively high actuating forces have to be summoned up first in order to move the brake caliper at all in a brake-effective manner. After the static friction has been overcome, these relatively high actuating forces however lead to an unexpectedly strong braking effect. In this connection one speaks of relative high “breakaway torques”. The driver may find this disturbing.
The document DE 10 2006 053 183 A1, and corresponding U.S. Pat. No. 8,220,596 B2, both of which are incorporated by reference herein in entirety, describes a solution whereby a slide bush of similar design is mounted directly on the guide bolt. This slide bush, instead of a radial groove extending in circumferential direction, has a series of grooves in the shape of a section of a helix, between which sliding surfaces likewise in the shape of a section of a helix are disposed. This solution similarly has the drawback of relatively large guiding surfaces which, if a vehicle has not been used for a prolonged period, then leads to the previously described high breakaway torques with the disadvantageous effect of unexpectedly strong braking effects.
The document DE 10 2007 053 902 A1, and corresponding US patent publication number 2010/282547 A1, both of which are incorporated by reference herein in entirety, further describes a solution whereby, instead of grooves in the shape of a section of a helix, axial grooves are provided. Between these axial grooves guiding surfaces likewise extending in axial direction are provided. This solution also leads to relatively high static friction forces that entail the described disadvantageous effect of high breakaway torques.
As further prior art, reference is made to the documents DE 100 04 178 A1, WO 2005/1241179 A1, WO 2004/038249 A1 and DE 102 45 027 A1. In these documents use is made i.a. of multipart guide bodies or guide bodies in the form of spring elements, which because of their complexity lead to arrangements that are relatively cost-intensive and hence rather less attractive for mass production.